Bio midterm
Chapter 1: Intro to Biology:
Definition of science
Confined to the natural world
Collect and organize info in an orderly way
Evidence is based on pure evidence and not beliefs/bias
Science is always changing and therefore never finished
Hypothesis
scientific explanation for a set of observations that can be tested in ways that support or reject it
Variables (ind. and dep.)
The independent variable is the variable being controlled in the problem, and the dependent variable is the variable that changes because of this control.
Theory
a very well supported explanation of a series of principles that occur in the natural world
Scientific methods
Scientific methodology involves observing and asking questions, making inferences, forming hypotheses, conducting controlled experiments, collecting and analyzing data, and drawing conclusions.
Limitations of science
Scientists must make ethical decisions when the safety of humans or animals is a factor in the experiment.
Science plays the role of ensuring scientific knowledge is unbiased/reliable and providing safety guidelines especially when testing on humans/animals
Science cannot make moral judgements because it is something only humans can decide
Bias
A bias is a particular preference or point of view that is personal rather than scientific; this means some scientific data can be misinterpreted or misapplied by scientists wanting to prove a point.
Energy Characteristics of life
Based on DNA code
2. Grow and develop
3. Respond to stimuli
4. Maintain stable internal environment
(homeostasis)
5. Made of Cells
6. Metabolise/Use energy
7. Reproduce
8. Evolve over generations.
Homeostasis
Organisms must react to changes in their environment to maintain homeostasis.
Homeostasis- The stable condition in which a living thing keeps itself.
Example: Maintaining a stable body temperature.
Observations
Metabolism -
Sum of all chemical reactions performed by a living thing to keep it alive.
Chapter 2: Chemistry of Life:
Parts of an atom
Atom is a basic unit of matter. It is made up of protons (+), neutrons (neutral), and electrons (-). They have an equal number of electrons and protons to balance out (only in neutral atom). Atoms are the individual smallest unit of an element.
Isotopes
Atoms of the same element that differ in the number of neutrons they contain
Changing the number of neutrons an element has will create an isotope
Ions
Slightly positively or slightly negatively charged atoms (simply: an unequally charged atom)
Changing the number of electrons an element has will form an ion
Element
A substance made up of only one type of atom. Examples include oxygen (O) and hydrogen (H).
Compound
A substance made up of two or more different elements chemically bonded together. Example: H₂O (water) is a compound made of hydrogen and oxygen.
Molecule
A group of two or more atoms bonded together. A molecule can consist of the same or different elements. Example: O₂ (molecular oxygen) is a molecule made of two oxygen atoms.
pH
measure of the amount of hydrogen ions (H+) or hydroxide ions (OH-) that would form if the substance was dissolved in water
x=7 → Neutral
x< 7 → acid (acidic)
x > 7 → Base (basic or alkaline)
Polarity
The uneven distribution of charge in a molecule due to differences in electronegativity (how strongly atoms attract electrons). Water is polar because oxygen is more electronegative than hydrogen.
Catalysts
Substances that speed up the rate of a chemical reaction and or lower the amount of activation energy needed to start the reaction
Enzymes
Proteins that act as biological catalysts
Covalent bonds
Bonds in which atoms share electrons
Ionic bonds
Bonds in which one atom gives away or takes an electron from another atom
Activation energy
The energy needed to get a chemical reaction started
Chemical reactions
A process that changes or transforms one set of chemicals into another
Valence electrons
Valence electrons are the electrons on the outermost electron “shell” or orbital of an atom and are the electrons that are accessible to other atoms to form covalent bonds or be given away to form an ionic bond
Special properties of water
Cohesion - attraction between molecules of the same substance
Adhesion - attraction between molecules of different substances
Polarity - water molecules have a partially positive charge on one end and a partially negative charge on the other end
Polarity gives water the ability to form hydrogen bonds - the attraction between a hydrogen atom with a partially positive charge and another atom with a partially negative charge
Universal solvent - water will dissolve all solutes to some degree
Ice is less dense than water
Water expands when it freezes
Basis of organic molecules
Carbon is the “backbone” for all living things
CHO - Carbohydrates
CHO - Lipids, but not a 1:2:1 ratio
CHON - proteins
CHONP - amino acids
Types of organic molecules
Carbonhydrates
Lipids
Proteins
Nucleic acids
Subunits of org. mol.
Carbs - simple sugars (monosaccharides)
Lipids
Proteins - amino acids
Nucleic acids - nucleotides
Chapters 3-6: Ecology:
Levels of ecology
Organism
Population
Community
Ecosystem
Biosphere
Biomass
The sum of all living tissue in a given trophic level
10% rule
The rule that 10% of energy from an organism being eaten (the prey) transfers to the consumer in the next trophic level
The remaining 90% of energy is lost as heat
The more levels apart a producer and consumer are on the food chain, the smaller amount of energy the consumer obtains from the producer
Niche
The range of physical and biological conditions in which a species obtains what it needs to survive and reproduce
Types of symbiosis
Symbiosis
A close, permanent relationship between organisms
Mutualism
The relationship between species in which both benefit
Parasitism
When one organism lives on or inside another, harming it– often taking the hosts nutritional needs
Commensalism
When one organism benefits but the other organism is not helped nor harmed
Aphotic/photic zone
Photic zone
The sunlit region near the water's surface in which photosynthesis can occur
Aphotic zone
The region below the photic zone in which photosynthesis cannot occur (there is not enough sunlight for photosynthesis to take place)
Benthos/Benthic zone
Benthos
Aquatic organisms that live in rocks and sediments on the bottom of lakes, streams, and oceans
Benthic zone
Where benthos live
If a benthic zone is below a photic zone, chemosynthetic autotrophs are the only primary producer
Geographic range
The area that a species inhabits
Species are more stable in large geographic ranges than smaller geographic ranges
Biodiversity
The total of all the genetically based variation in all organisms in the biosphere
Monoculture/large scale farming
Planting large amounts of a single variety of a crop
This can be risky because if there is a limiting factor, it can wipeout the entire field
Exponential growth
The idea that the larger a population gets, the faster it will grow (J curve)
Immigration/emigration
Immigration
When individuals move into a population’s range from elsewhere
Emmigration
When individuals move out of a population’s range
Desertification
When relatively productive land is turned into desert
Types of autotrophs
photoautotrophs: make food through photosynthesis
chemoautotrophs: make food through chemosynthesis
Trophic level labels
producer (1st trophic level)
ex. plant
primary consumer (2nd trophic level)
ex. grasshopper
secondary consu mer (3rd trophic level)
ex. frog
tertiary consumer (4th trophic level)
ex. snake
Food chains/webs
food chain: a series of steps in which organisms transfer energy by eating and being eaten
food web: a network of feeding interactions; several organisms eat several species of organisms
Sources of energy for food chains
sun (photosynthesis)
Ecological pyramids
the relative amount of energy or matter contained within each trophic level in a given food chain or food web
pyramid of energy
pyramid of biomass
pyramid of numbers
Decomposers
absorb energy by breaking down dead stuff into detritus (dirt)
ex. fungi
Water cycle
Carbon cycle
Nitrogen fixation
a chemical process that converts atmospheric nitrogen into ammonia, which is absorbed by organisms
essentially converting atmospheric nitrogen into a form that plants can more readily utilize
Sources of nitrogen for pl. and an.
Habitat
-the general place where an organism lives
Greenhouse effect
-allows visible light to enter and traps heat. It is natural and needs to happen for Earth to be survivable, but too much is dangerous and leads to global warming/climate change
Energy vs. matter in ecosystems
energy flows, matter cycles
Limiting factors
-factors that control the growth of a population; determine the carrying capacity of an environment for a species
- can be amount of sunlight, nutrients,competition, predation. (I think??)
Weather vs. climate
-Weather is the day-to-day condition of Earth's atmosphere; short term properties of troposphere
-Climate refers to average conditions over long periods - year after year of temperature and precipitation
Predator/prey rel.
-populations of both cycle up and down - affect each other
Predator
The consumer, the organism higher on the food chain
Prey
The organism being hunted, consumed
Primary/secondary succession
Succession - a series of changes that takes place in a community from its start until it reaches a stable equilibrium
Primary - succession that begins in an area with no remnants of an older community - starts from barren rock, no soil, takes a long time (100s of years)
Secondary - when a community is not completely destroyed by a disturbance; secondary succession in healthy ecosystems following natural disturbances often reproduce the original climax community
R-selected species:
fast reproduction/rapid growth
quick evolution
low offspring survival rate
short life span
K-selected species:
slow reproduction/slow growth
high survival rate
found mostly in stable environments
ex. humans and elephants
better climax community - establish themselves, more predominant, still there after 100s of years
Determining terrestrial biomes
-described in terms of abiotic factors like climate, temperature, precipitation, and soil type, and biotic factors like plant and animal life (even within a biome there is a large variation among plant and animal communities
Pop. distribution
-how the individuals in a population are spaced out across the range of the population
Types of aquatic ecosystems
-Freshwater - rivers and streams, lakes and ponds, and freshwater wetlands.
-Estuary - mix of fresh and saltwater
-Ocean - consists of multiple zones
- intertidal zone (submerged at high tide, exposed at low tide, hit by waves),
- coastal ocean (low-tide mark to outer edge of continental shelf, lots of nutrients, brightly lit, kelp and coral)
- open ocean (beyond continental shelf, greater than 90% of ocean, 500m - 10km deep, two zones)
-in open ocean there are two zones are
photic: top 100m, low nutrient but photosynthesis,
aphotic: deepest part, chemosynthesis, high pressure, cold, deep-sea vents.
Population density
-the number of individuals per unit of area
Age structure
-age structure diagrams can help predict population growth, can compare populations and age structures, consider many factors to predict how the world's population will grow, breaks down population into age ranges, can be used to indicate degree of population growth.
Birthrate/deathrate
-birth rate - number of births per thousand of population each year
-death rate - number of deaths per thousand of population each year
Logistic growth
-Phase 1: exponential growth - resources are unlimited, individuals grow and reproduce rapidly, few die, population size and rate of growth increase exponentially
Phase 2: growth slows down - rate of population slows down, population size does not decrease, population still grows but slower
Phase 3: growth stops - rate of population zero, size of population levels off
Logistic growth occurs when a population's growth slows and then stops, following a period of exponential growth
Carrying capacity
- maximum number of individuals of a particular species that a particular environment can support
Density dep. vs. density ind. limiting factors
-Density dependent limiting factors work strongly only when population density reaches a certain level - includes competition, predation, herbivory, parasitism, disease, and stress from overcrowding
-Density independent limiting factors affect all populations in similar ways, regardless of population size and density
Demographic transition
-Demography - scientific study of human populations
-Demographic transition - a dramatic change from high birthrates and death rates to low birthrates and death rates
Invasive/introduced species
species introduced to areas where they don’t traditionally grow
begin reproducing in the new habitat
cometimes outcompete native species (harmful to ecosystem)
Sustainable development
Renewable/nonrenewable resources
renewable: can be replaced if properly managed
Ex. collar energy, wind, vegetation
nonrenewable: cannot be replenished on a human time scale
Ex. fossil fuels, oil, natural gas
Biomagnification
when a pollutants is picked up by an organism and isn’t broken down or eliminated from the body and instead collected in body tissue
Acid rain
water vapor mixed with compounds that form nitric acid and sulfuric acids
Smog
a gray-brown haze formed by chemical reactions among pollutants released into the air by industrial processes and automobiles
Threats to biodiversity
habitat loss
pollution
overexploitation
invasive species
climate change
Chapters 7: Cells:
Cell theory
All organisms are composed of one or more cells
The cell is the basic unit of organization of organisms
All cells come from preexisting cells
Prokaryote/eukaryote- defining characteristics
-Prokaryotic - smaller, simpler type of cells. Do not contain membrane bound organelles, do not have a nucleus, DNA is scattered around inside the cell, always unicellular organisms (organisms made up of one cell) ex. bacteria
-Eukaryotes - larger, more complex type of cells, contains organelles, including a nucleus, DNA of these cells are contained in nuclei, can be unicellular or multicellular organisms (one or many cells) ex. all plants and animals
Organelles
-parts of cells, like mini organs, do specific functions that help the cell function. They are small specialized structures inside of a cell that are contained within a membrane.
- need to know all the organelles in a cell
Plant vs. animal cells
-Plant cells have cell walls, which is a rigid outer covering of the cell, helping the cell maintain its shape and rigidity. They also have chloroplasts, which contains a substance called chlorophyll, traps energy from sunlight and converts it into a more usable form (sugar), belongs to group of organelles called plastids, most of which are used for storage.
-Animal cells have centrioles, which are structures containing microtubules, which helps cell divide (cell reproduction). They also have cilia, which are small hair-like projections on the outside of cells, wave back and forth to move the cell or move things around outside of the cell. They do not have cell walls. Finally, they have flagella, which is a long tail-like projection from a cell that can beat back and forth to propell the cell.
Cell membrane
-in plants, inside of the cell wall; in animals, the outermost layer. Mainly composed of a phospholipid bilayer.
Purpose of the cell membrane is to control what enters and exits the cell - maintains homeostasis in the cell. It is selectively permeable, meaning it allows in some molecules, while keeping others out. The gateway in and out of the cell are the proteins in the molecule.
Bilayer - because the molecule is polar, the phosphate heads which are charged the same repel each other. Made of proteins, cholesterol, carbohydrate chains.
Levels of biological organization (smallest to largest)
atom
molecule
organelle
cell
tissue
organ
organ system
organism
population
community
ecosystem
biosphere
Homeostasis
Definition
-Homeostasis is the process by which living organisms maintain a stable internal environment despite external changes. This includes regulating factors like temperature, pH, and water balance to keep the body functioning properly.
Examples of conditions - body temp?
pH/Buffers
-pH is a measurement scale to indicate the concentration of H* ions in a solution. Acids are 0-6, while bases or alkaline are 8-14 and 7 is neutral (whole scale is 0-14). Bases have more hydroxide (H-) while acids have more hydrogen (H+).
Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH.
Maintenance at varying levels (organism, cellular) Application to Ecology
Enzymes
Proteins that act as biological catalysts
Speed up chemical reactions and or reduce the activation energy to start a reaction